package cn.com.elite;

import java.io.FileInputStream;  
import java.io.FileOutputStream;  
import java.io.InputStream;  
import java.io.OutputStream;  
import java.security.Key;  
import java.security.SecureRandom;  
   
import javax.crypto.Cipher;  
import javax.crypto.CipherInputStream;  
import javax.crypto.CipherOutputStream;  
import javax.crypto.KeyGenerator;  
   
import sun.misc.BASE64Decoder;  
import sun.misc.BASE64Encoder;  
   
public class DESUtil {  
   
    Key key ;  
   
    public DESUtil() {  
   
    }  
   
    public DESUtil(String str) {  
       setKey(str); // 生成密匙  
    }  
   
    public Key getKey() {  
       return key ;  
    }  
   
    public void setKey(Key key) {  
       this . key = key;  
    }  
   
    /** 
      * 根据参数生成 KEY 
      */  

    public void setKey(String strKey) {  
       try {  
           KeyGenerator _generator = KeyGenerator.getInstance ( "DES" );  
           _generator.init( new SecureRandom(strKey.getBytes()));  
           this . key = _generator.generateKey();  
           _generator = null ;  
       } catch (Exception e) {  
           throw new RuntimeException(  
                  "Error initializing SqlMap class. Cause: " + e);  
       }  
    }  
   
    /** 
      * 加密 String 明文输入 ,String 密文输出 
      */  
    public String encryptStr(String strMing) {  
       byte [] byteMi = null ;  
       byte [] byteMing = null ;  
       String strMi = "" ;  
       BASE64Encoder base64en = new BASE64Encoder();  
       try {  
           byteMing = strMing.getBytes( "UTF8" );  
           byteMi = this .encryptByte(byteMing);  
           strMi = base64en.encode(byteMi);  
       } catch (Exception e) {  
           throw new RuntimeException(  
                  "Error initializing SqlMap class. Cause: " + e);  
       } finally {  
           base64en = null ;  
           byteMing = null ;  
           byteMi = null ;  
       }  
       return strMi;  
    }  
   
    /** 
      * 解密 以 String 密文输入 ,String 明文输出 
      * 
      * @param strMi 
      * @return 
      */  
    public String decryptStr(String strMi) {  
       BASE64Decoder base64De = new BASE64Decoder();  
       byte [] byteMing = null ;  
       byte [] byteMi = null ;  
       String strMing = "" ;  
       try {  
           byteMi = base64De.decodeBuffer(strMi);  
           byteMing = this .decryptByte(byteMi);  
           strMing = new String(byteMing, "UTF8" );  
       } catch (Exception e) {  
           throw new RuntimeException(  
                  "Error initializing SqlMap class. Cause: " + e);  
       } finally {  
           base64De = null ;  
           byteMing = null ;  
           byteMi = null ;  
       }  
       return strMing;  
    }  
   
    /** 
      * 加密以 byte[] 明文输入 ,byte[] 密文输出 
      * 
      * @param byteS 
      * @return 
      */  
    private byte [] encryptByte( byte [] byteS) {  
       byte [] byteFina = null ;  
       Cipher cipher;  
       try {  
           cipher = Cipher.getInstance ( "DES" );  
           cipher.init(Cipher. ENCRYPT_MODE , key );  
           byteFina = cipher.doFinal(byteS);  
       } catch (Exception e) {  
           throw new RuntimeException(  
                  "Error initializing SqlMap class. Cause: " + e);  
       } finally {  
           cipher = null ;  
       }  
       return byteFina;  
    }  
   
    /** 
      * 解密以 byte[] 密文输入 , 以 byte[] 明文输出 
      * 
      * @param byteD 
      * @return 
      */  
    private byte [] decryptByte( byte [] byteD) {  
       Cipher cipher;  
       byte [] byteFina = null ;  
       try {  
           cipher = Cipher.getInstance ( "DES" );  
           cipher.init(Cipher. DECRYPT_MODE , key );  
           byteFina = cipher.doFinal(byteD);  
       } catch (Exception e) {  
           throw new RuntimeException(  
                  "Error initializing SqlMap class. Cause: " + e);  
       } finally {  
           cipher = null ;  
       }  
       return byteFina;  
    }  
   
    /** 
      * 文件 file 进行加密并保存目标文件 destFile 中 
      * 
      * @param file 
      *             要加密的文件 如 c:/test/srcFile.txt 
      * @param destFile 
      *             加密后存放的文件名 如 c:/ 加密后文件 .txt 
      */  
    public void encryptFile(String file, String destFile) throws Exception {  
       Cipher cipher = Cipher.getInstance ( "DES" );  
       // cipher.init(Cipher.ENCRYPT_MODE, getKey());  
       cipher.init(Cipher. ENCRYPT_MODE , this . key );  
       InputStream is = new FileInputStream(file);  
       OutputStream out = new FileOutputStream(destFile);  
       CipherInputStream cis = new CipherInputStream(is, cipher);  
       byte [] buffer = new byte [1024];  
       int r;  
       while ((r = cis.read(buffer)) > 0) {  
           out.write(buffer, 0, r);  
       }  
       cis.close();  
       is.close();  
       out.close();  
    }  
   
    /** 
      * 文件采用 DES 算法解密文件 
      * 
      * @param file 
      *             已加密的文件 如 c:/ 加密后文件 .txt * 
      * @param destFile 
      *             解密后存放的文件名 如 c:/ test/ 解密后文件 .txt 
      */  
    public void decryptFile(String file, String dest) throws Exception {  
       Cipher cipher = Cipher.getInstance ( "DES" );  
       cipher.init(Cipher. DECRYPT_MODE , this . key );  
       InputStream is = new FileInputStream(file);  
       OutputStream out = new FileOutputStream(dest);  
       CipherOutputStream cos = new CipherOutputStream(out, cipher);  
       byte [] buffer = new byte [1024];  
       int r;  
       while ((r = is.read(buffer)) >= 0) {  
           cos.write(buffer, 0, r);  
       }  
       cos.close();  
       out.close();  
       is.close();  
    }  
   
    public static void main(String[] args) throws Exception {  
       DESUtil des=new DESUtil("1234567");  
       // DES 加密文件  
       // des.encryptFile("G:/test.doc", "G:/ 加密 test.doc");  
       // DES 解密文件  
       // des.decryptFile("G:/ 加密 test.doc", "G:/ 解密 test.doc");  
       String str1 = " 要加密的字符串 test" ;  
       // DES 加密字符串  
       String str2 = des.encryptStr(str1);  
       // DES 解密字符串  
       String deStr = des.decryptStr(str2);  
       System. out .println( " 加密前： " + str1);  
       System. out .println( " 加密后： " + str2);  
       System. out .println( " 解密后： " + deStr);  
    }  
}   
